Removal of hydrogen sulfide as ammonium sulfate from hydropyrolysis product vapors

ABSTRACT

A system and method for processing biomass into hydrocarbon fuels that includes processing a biomass in a hydropyrolysis reactor resulting in hydrocarbon fuels and a process vapor stream and cooling the process vapor stream to a condensation temperature resulting in an aqueous stream. The aqueous stream is sent to a catalytic reactor where it is oxidized to obtain a product stream containing ammonia and ammonium sulfate. A resulting cooled product vapor stream includes non-condensable process vapors comprising H 2 , CH 4 , CO, CO 2 , ammonia and hydrogen sulfide.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/196,645, filed Aug. 2, 2011, now allowed, which is herebyincorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to a process that removes hydrogen sulfide (H₂S)from product vapors exiting a Hydropyrolysis reactor via reaction withammonia (NH₃) to form ammonium sulfide. In addition, the processconverts hydrogen sulfide to ammonium sulfate.

DESCRIPTION OF RELATED ART

The process of the present invention relates to removal of H₂S from theeffluent vapors exiting a hydropyrolysis reactor. Hydropyrolysisreactors are known in the art.

Commercially, H₂S is commonly removed from vapor streams via the Clausprocess, in a Claus plant. In the Claus Process, H₂S is oxidized to formsulfur dioxide (SO₂) and then the sulfur dioxide is reacted with moreH₂S to produce water (H₂O) and elemental sulfur. The overall reactionis:

2H₂S+O₂→S₂+2H₂O

This process is well-known, and has been widely applied in the refiningand reforming of petroleum products. However, the process is complex,and often involves multiple reaction steps. Moreover, the process can bemost efficiently applied to streams containing 25% or more of H₂S, on amolecular basis. If streams containing ammonia, as well as H₂S areprocessed in a Claus plant, the ammonia is oxidized along with the H₂S.This is not desirable, because ammonia is a potentially-valuablereaction product of the hydropyrolysis process.

A significant portion of the product vapor stream from thehydropyrolysis reactor comprises water vapor and hydrocarbons withboiling points below 70 degrees Fahrenheit, at atmospheric pressure. Theproduct vapor from the hydropyrolysis reactor must be cooled to ambienttemperatures in order for liquid hydrocarbons to be recovered as aseparate product stream. When the product vapor stream is cooled, watervapor in the product vapor stream condenses to form liquid water, and asignificant fraction of any H₂S and any NH₃ in the product vapor streamgo into solution in the liquid water. The resulting aqueous solutionthen contains ammonia and sulfide compounds.

Processes by which water-soluble sulfide compounds can be catalyticallyreacted with oxygen to form stable sulfate compounds are disclosed inMarinangeli et al., U.S. Pat. No. 5,207,927 Gillespie, U.S. Pat. No.5,470,486. The approach taught by Marinangeli et al., involves passingan aqueous stream containing both the sulfide compound and oxygen overan appropriate oxidizing catalyst, under conditions wherein the pH ofthe solution is 9-12, and an oxygen-to-sulfur ratio greater than about 5is maintained. The approach taught by Gillespie requires a pH greaterthan 12 and an oxygen-to-sulfur ratio greater than about 4 bemaintained. Both approaches prefer metal phthalocynanines with Gillespiepreferring the use of carbon supports. A product stream that issubstantially free of sulfide compounds is thus obtained, since allsulfide compounds have been converted to sulfate compounds.

SUMMARY OF THE INVENTION

In the hydropyrolysis reactor of the process of the present invention, abiomass feedstock is converted into a stream containing the following:

-   -   1. Deoxygenated condensable hydrocarbons (with properties        corresponding to those of gasoline, diesel and kerosene)    -   2. Non-condensable hydrocarbon vapors (such as methane, ethane,        propane and butane),    -   3. Other non-condensable vapors (CO₂, CO, and hydrogen),    -   4. Water and species which are soluble in liquid water, such as        ammonia (NH₃), and hydrogen sulfide (H₂S).

The NH₃ is present in the hydropyrolysis product stream due to thepresence of nitrogen in the biomass feedstock. The H₂S is present in thehydropyrolysis stream due to the presence of sulfur in the biomassfeedstock. The nitrogen and the sulfur in the feedstock react withhydrogen in the hydropyrolysis reactor to form NH₃ and H₂S,respectively.

It is one object of this invention to provide a method by which hydrogensulfide can be removed from a product vapor stream, produced by thehydropyrolysis of biomass. Hydropyrolysis experiments, in the course ofwhich biomass was deoxygenated and converted to products includinghydrocarbons, have shown that the stream of vapor leaving thehydropyrolizer contains water vapor, NH₃, and H₂S, in proportions thatmake this product uniquely suited to a process in which the H₂S iscombined with the NH₃ in an aqueous solution, and then oxidized to formammonium sulfate. These experiments are original, and the concentrationsof nitrogen and sulfur compounds in the vapor stream are unexpected andsurprising. The experiments are described in detail in the examplespresented below.

In order to carry out hydropyrolysis in the hydropyrolysis reactorassociated with the present invention, some portion of thehydropyrolysis product stream from the reactor may be sent to a steamreformer, and there reacted with steam to produce hydrogen. Generally,it will be desirable to send some or all of the non-condensablehydrocarbon vapors, such as methane, ethane, butane, etc., to thereformer. The hydrogen thus obtained may then be introduced back intothe hydropyrolysis reactor, so that hydropyrolysis can continue to becarried out. The need for a source of hydrogen, external to thehydropyrolysis process associated with the present invention, may thusbe reduced or eliminated. Note that H₂S will be present in the productvapor stream from the hydropyrolysis process whenever sulfur is presentin the feedstock, and the presence of the H₂S creates several problems.

The H₂S in the product vapor stream is highly toxic to humans. Inaddition, the H₂S can poison the catalysts involved in steam reformingof product vapors from the hydropyrolysis reactor. Moreover, the H₂S canbe reacted with NH₃ to produce ammonium sulfide ((NH₄)₂S), and thenoxidized to produce ammonium sulfate ((NH₄)₂SO₄), a product withconsiderable commercial value as a fertilizer.

The present invention describes a process which allows the H₂S and NH₃contained in product vapor from hydropyrolysis of biomass to be capturedin an aqueous stream. Biomass hydropyrolysis experiments havedemonstrated that the hydropyrolysis process associated with the presentinvention produces a product stream that contains water vapor, H₂S, andNH₃ in particular quantities that make it possible to obtain therequisite conditions for H₂S removal via conversion to (NH₄)₂SO₄.Substantially all the H₂S captured in the aqueous stream is reacted withNH₃ to form (NH₄)₂S. In addition, a surplus of unreacted NH₃ is providedand dissolved in the aqueous stream, in order to increase the pH of theaqueous stream to approximately 12 or greater or lesser as required forsubsequent conversion of (NH₄)₂S to (NH₄)₂SO₄. The stream can then bereacted with oxygen in a thermal, non-catalytic conversion zone tosubstantially convert the dissolved (NH₄)₂S to (NH₄)₂SO₄ andthiosulfate. The stream can be further contacted with oxygen and anoxidizing catalyst in accordance with the method disclosed in Gillespie,U.S. Pat. No. 5,470,486 or, alternatively, the incoming aqueous streamcan be reacted with oxygen, in the presence of an appropriate catalyst,in accordance with the method disclosed in the U.S. Pat. No. 5,207,927(Marinangeli, et al.). By employing either technology, within the rangesof pH, oxygen to sulfur mole ratio, pressure, temperature, and liquidhourly space velocities taught in these patents, an aqueous streamcontaining NH₃ and (NH₄)₂SO₄ is thereby obtained, and these compoundscan then be recovered and sold as fertilizer. A variety of methods forobtaining ammonium sulfate from an aqueous stream containing ammoniumsulfite and dissolved ammonia are currently in use and the examplescited above serve to illustrate that established technologies exist foreffecting this conversion.

These ammonia-derived compounds that can be recovered and sold asfertilizer can be mixed with char produced by this process andpelletized to produce a product to provide fertilize and amend soils.Likewise these ammonia-derived compounds produced by this process thatcan be recovered and sold as fertilizer can also be mixed with char andother essential soil nutrients and minerals and pelletized to produce aproduct to provide improve, fertilize, and amend soils. It should alsobe obvious to one skilled in the art that these ammonia-derivedcompounds that incorporate char and other essential soil nutrients andminerals can be prepared in time-release formulations to avoidrepetitive applications in an agricultural setting.

A stream of product vapor, from which substantially all the H₂S has beenremoved, is also obtained. This stream of vapor can then be handled invarious ways, including use as a fuel to raise steam or directing itinto a steam reformer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of this invention will be betterunderstood from the following detailed description taken in conjunctionwith the drawings wherein:

FIG. 1 shows a process flow diagram according to one preferredembodiment of this invention, in which H₂S is captured in a primaryaqueous stream containing NH₃, and oxidized in a reactor to form(NH₄)₂SO₄.

FIG. 2 shows a process flow diagram according to one preferredembodiment of this invention, in which H₂S that still remains in thecooled vapor product stream is captured in a sorbent bed.

FIG. 3 shows a process flow diagram according to one preferredembodiment of this invention, in which the H₂S remaining in the cooledvapor product stream is captured and sent into the oxidation reactoralong with the primary aqueous stream, promoting more complete overallconversion of H₂S to (NH₄)₂SO₄.

FIG. 4 shows a process flow diagram according to one preferredembodiment of this invention, in which the treated aqueous productstream, containing water, NH₃, and (NH₄)₂SO₄, is treated in a sour-gasstripper.

FIG. 5 shows a process flow diagram according to one preferredembodiment of this invention, in which a sour-water stripper removes NH₃and H₂S from the primary aqueous stream prior to the introduction of theaqueous stream to the oxidation reactor.

FIG. 6 shows a process flow diagram according to one preferredembodiment of this invention, which incorporates both an H₂S removalunit, associated with the cooled vapor product stream, and a sour-waterstripper upstream of the oxidation reactor.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIGS. 1-6 show various preferred embodiments of the subject invention.FIG. 1 shows a process flow diagram, illustrating the simplestembodiment of the process of the present invention, in which H₂S iscaptured in a primary aqueous stream containing NH₃, and oxidized in areactor to form (NH₄)₂SO₄. Product streams in this embodiment include acooled vapor stream comprising primarily process vapors, and containingsome H₂S, a liquid stream comprising primarily condensed hydrocarbons, asecond vapor stream comprising primarily nitrogen and oxygen, and atreated aqueous stream comprising primarily water, NH₃, and (NH₄)₂SO₄.

FIG. 1 shows the first and most elementary embodiment of the process ofthe present invention. Biomass 111 and hydrogen 112 are introduced intoa hydropyrolizer 110, which produces a solid, carbonaceous product 113(referred to as char) and a product vapor stream 114. The solid product113 comprises primarily carbonaceous residue, remaining after thehydropyrolysis of the biomass feedstock 111. The product vapor stream114 leaves the hydropyrolizer 110 (which may comprise a single reactor,or multiple reactors in series) at a temperature that is characteristicof such hydropyrolytic processes, at a minimum, high enough that allconstituents are maintained in a gaseous state. However, as ischaracteristic of such hydropyrolytic conversion processes, thetemperature may also be significantly higher than this minimum. Theproduct vapor stream 114 primarily comprises:

-   -   1. Deoxygenated condensable hydrocarbons (with properties        corresponding to those of gasoline, diesel and kerosene)    -   2. Non-condensable hydrocarbon vapors (such as methane, ethane,        propane and butane),    -   3. Other non-condensable vapors (CO₂, CO, and H₂),    -   4. Water and species which are soluble in liquid water, such as        ammonia (NH₃), and hydrogen sulfide (H₂S).

The vapor stream is passed through a condenser 120, or other device, orother set of devices, wherein the temperature of the vapor stream isreduced to a point where substantially all the condensable hydrocarbonscan be recovered as a liquid stream. At this point, three phasesdevelop: A cooled vapor phase, a hydrocarbon phase, and an aqueousphase. The cooled product stream, containing all three phases, is sentto a separator 130, where the three phases can be split up into threeseparate streams.

The condensable hydrocarbon product stream 132 is preferably recoveredat this point. The H₂S that was initially in the hot product vaporstream 114 is now divided, with some exiting the separator in the cooledvapor stream 131, and some in the primary aqueous stream 133. A trace ofH₂S may also be present in the liquid hydrocarbon stream 132, but thesolubility of the polar H₂S molecule in the liquid hydrocarbon stream isminimal.

The cooled vapor product stream 131 leaving the separator comprisesprimarily H₂, non-condensable hydrocarbons, CO₂, CO, and H₂S.

The primary aqueous stream 133 leaving the separator comprises primarilywater, NH₃, and ammonium sulfide ((NH₄)₂S). The (NH₄)₂S in this streamis produced when the H₂S from the vapor stream enters the aqueous streamand reacts with NH₃, which is also in solution in the aqueous stream. Itis an object of this invention to control the process of the inventionin such a manner that the pH of the primary aqueous stream 133 isapproximately 12, meaning that the concentration of NH₃ (as NH₄OH) inthe stream is great enough to produce a strongly-basic solution. This ishelpful, in part, to help stabilize the H₂S and increase its solubilityin the aqueous stream. It is also a preferred condition for theoperation of the oxidation reactor 140, wherein the (NH₄)₂S is oxidizedto produce (NH₄)₂SO₄.

The primary aqueous stream 133 from the separator 130 is then introducedto an oxidation reactor 140, also referred to as a catalytic reactorherein. A stream of air 141 is also introduced to the oxidation reactor,in an amount sufficient to supply approximately 5 moles of oxygen foreach mole of sulfur. After reaction at an appropriate temperature andpressure, in the presence of an appropriate catalyst, and for asufficient residence time, the (NH₄)₂S in the primary aqueous stream 133is substantially completely oxidized.

In accordance with this first embodiment of the process of the presentinvention, a treated aqueous product stream 142 is preferably obtainedfrom the oxidation reactor, including NH₃, liquid water, and (NH₄)₂SO₄.In addition, a reactor gas product stream 143 is obtained from theoxidation reactor, primarily comprising nitrogen and unused oxygen, andcontaining traces of NH₃ and water vapor. It will be noted that, in thisfirst embodiment, a significant concentration of H₂S is still present inthe cooled product vapor stream 131 exiting the separator unit 130.

FIG. 2 is a process flow diagram, illustrating an embodiment of theprocess of the present invention, in which H₂S that still remains in thecooled vapor product stream is captured in a sorbent bed. In this case,removal of the H₂S remaining in the cooled product vapor stream issubstantially complete.

FIG. 2 illustrates a second embodiment of the process of the presentinvention. In this second embodiment an H₂S removal unit 250 has beenadded, downstream of the separator 230. The primary cooled vapor productstream 231 passes through the H₂S removal unit 250 (which may comprise asorbent bed, liquid wash, or other similar apparatus). The H₂S in theprimary cooled vapor product stream 231 is substantially completelyremoved from the primary cooled vapor product stream 231, and asecondary cooled vapor product stream 251 comprising primarily H₂, CO,CO₂, and non-condensable hydrocarbon vapors is obtained. In thisembodiment, the H₂S is not recovered, and would, for example, bedisposed of when the H₂S removal unit 250 is regenerated withH₂S-containing waste being appropriately discarded.

FIG. 3 illustrates a third embodiment of the process of the presentinvention. In this third embodiment, an H₂S removal unit 350 has beenadded, downstream of the separator 330, as in the second embodiment,described above. The primary cooled vapor product stream 331 passesthrough the H₂S removal unit 350 (which may comprise a reusable sorbentbed, amine scrubber, or some similar apparatus). The H₂S in the primarycooled vapor product stream 331 is substantially completely removed, anda secondary cooled vapor product stream 351 comprising primarily H₂, CO,CO₂, and non-condensable hydrocarbon vapors is obtained. However, inthis third embodiment, the H₂S is recovered from the H₂S removal unit350, in a stream 352 comprising primarily gaseous H₂S, and is sent tothe oxidation reactor 340, along with the primary aqueous stream 333. Inthe oxidation reactor, the gaseous H₂S stream 352 is brought intocontact with the primary aqueous stream 333 and an appropriate catalyst,and forms (NH₄)₂S, which is then oxidized to form (NH₄)₂SO₄. In thisway, a secondary cooled product vapor stream 351, containing only traceamounts of H₂S, and comprising primarily H₂, non-condensablehydrocarbons, CO₂, and CO, is obtained. In addition, the overallconversion of H₂S is increased, and is higher than in the firstembodiment of the process of the present invention, described above.

FIG. 4 illustrates a fourth embodiment of the process of the presentinvention. Ammonia (NH₃) is a potentially-valuable product, and isseparated from the primary treated aqueous stream 442 leaving theoxidation reactor 440 in a sour-water stripper 460 in this fourthembodiment of the process of the present invention. This approach allowsa gaseous stream 461 comprising primarily NH₃ to be recovered, while thewater and (NH₄)₂SO₄ are recovered separately from the sour-waterstripper in a secondary treated aqueous stream 462. (NH₄)₂SO₄ is highlywater-soluble, and the aqueous solution of (NH₄)₂SO₄ has potential valueas an agricultural fertilizer. If desired, this solution can beconcentrated by further heating of the secondary treated aqueous stream462, which could drive off some or all of the water in, the stream.

FIG. 5 illustrates a fifth embodiment of the process of the presentinvention. This embodiment features a sour-water stripper 560 upstreamof the oxidation reactor 540, which accepts the primary aqueous stream533 from the separator. Water, NH₃ and H₂S, and any (NH₄)₂S formed bythe reaction of NH₃ and H₂S, are removed in the sour-water stripper 560,and leave the sour-water stripper as a gaseous stream 562. A stream ofpurified liquid water 561 is thereby produced. This purified waterstream 561 is then available as a product stream. If desired, a portionof this purified water stream 561 can be brought back into contact withthe gaseous stream 562 of NH₃ and H₂S from the sour-water stripper. Inthis case, the NH₃ and H₂S go back into solution in this portion of theliquid water stream 561, forming (NH₄)₂S, and this solution is thenintroduced into the oxidation reactor 540, for conversion to (NH₄)₂SO₄.However, preferably the purified water stream is not brought back intocontact with the gaseous stream 562 and preferably, stream 562 is cooledas needed so that water in the stream is condensed and the NH₃ and H₂Sin this stream go back into solution forming (NH₄)₂S, and this solutionis then introduced into the oxidation reactor 540, for conversion to(NH₄)₂SO₄. This approach makes a stream of purified water 561 available,and creates a concentrated treated stream 542 of water, NH₃ and(NH₄)₂SO₄ at the outlet of the oxidation reactor 540.

FIG. 6 illustrates a sixth embodiment of the process of the presentinvention. This embodiment features a sour-water stripper 660 upstreamof the oxidation reactor 640, which accepts the primary aqueous stream633 from the separator 630. It also features an H₂S removal unit 650downstream of the separator 630, as in the third embodiment describedherein above. The primary cooled vapor product stream 631 passes throughthe H₂S removal unit 650 (which may comprise a sorbent bed, aminescrubber, or some similar apparatus). The H₂S in the primary cooledvapor product stream 631 is substantially completely removed and asecondary cooled product vapor stream 651 comprising primarily H₂, CO,CO₂, and non-condensable hydrocarbon vapors is obtained. As in the thirdembodiment, the H₂S is recovered, in a stream 652 comprising primarilygaseous H₂S, and is sent to the oxidation reactor 640.

As described herein above in the description of the fifth embodiment,dissolved NH₃ and H₂S, and any (NH₄)₂S formed by the reaction of NH₃ andH₂S, are driven out of the primary aqueous stream 633 in the sour-waterstripper 660. Water, NH₃ and H₂S, and any (NH₄)₂S formed by the reactionof NH₃ and H₂S, are removed in the sour-water stripper 660, and leavethe sour-water stripper as a gaseous stream 662. A stream of purifiedwater 661 is thereby produced. This purified water stream 661 is thenavailable as a product stream. If desired, a portion of this purifiedwater stream 661 can be brought back into contact with the gaseousstream 662 of NH₃ and H₂S from the sour-water stripper. In this case,the NH₃ and H₂S go back into solution in this portion of the liquidwater stream 661, forming (NH₄)₂S, and this solution is then introducedinto the oxidation reactor 640, for conversion to (NH₄)₂SO₄. However,preferably the purified water stream is not brought back into contactwith the gaseous stream 662 and preferably, stream 662 is cooled asneeded so that water in the stream is condensed and the NH₃ and H₂S inthis stream go back into solution forming (NH₄)₂S, and this solution isthen introduced into the oxidation reactor 640, for conversion to(NH₄)₂SO₄. This approach makes a stream of purified water 661 available,and creates a concentrated treated stream 642 of water, NH₃ and(NH₄)₂SO₄ at the outlet of the oxidation reactor 540. The stream 652 ofrecovered H₂S from the H₂S removal unit is also introduced to theoxidation reactor.

This sixth embodiment of the process of the present invention makes astream of purified water 661 available, and creates a concentratedtreated stream 642 of water, NH₃ and (NH₄)₂SO₄ at the outlet of theoxidation reactor 640. It also provides a secondary stream of cooledvapor product 651 which may contain minute concentrations of H₂S, andpromotes high overall conversion of H₂S to an (NH₄)₂SO₄ product.

The char produced from the hydropyrolysis of biomass (land and waterbased biomass, wastes from processes utilizing these materials), as wellas plastics derived from biomass or petroleum has been found to be anessentially inert carbonaceous material, free of hydrocarboncontaminants that are toxic to humans or plants. It is one intent ofthis invention to combine the char produced from the hydropyrolysis ofbiomass or plastic with the ammonium sulfate recovered from this processto produce an agricultural fertilizer product, as a powder, granulated,or pelletized material that can both improve the quality of a soil foruse as an agricultural substrate and provide a fertilizing component forthe sustenance of lignocellulosic biomass.

EXAMPLES

A sample of wood with properties representative of those of most woodspecies was subjected to hydropyrolysis. The elemental composition ofthe wood is presented in Table A, below. The composition is presented onboth an overall basis (which includes moisture and ash in the feedstock)and on a moisture- and ash-free (MAF) basis. As can be seen in Table A,small but significant quantities of nitrogen and sulfur were present inthe wood.

The yield of hydropyrolysis products, obtained in the vapor streamleaving the experimental hydropyrolizer, is given in Table B. Not all ofthe nitrogen and sulfur initially present in the wood is ultimatelyfound in the vapor stream from the hydropyrolizer. Some of the sulfurand some of the nitrogen are chemically bound up in the stream of solidproduct (comprising char and ash) from the hydropyrolizer. However, theexperiment demonstrated that the yield of NH₃ in the primary productvapor stream constituted 0.18% of the mass of the feedstock, on an MAFbasis. The yield of H₂S constituted 0.05% of the mass of the feedstock,on an MAF basis. It will be noted that the total masses in Table B addup to 104.83%. This is due to the fact that a given quantity of moistureand ash-free wood reacts with hydrogen in the hydropyrolysis process,and the resulting products have a greater total mass than the wood thatwas reacted.

As an example, one might assume that one kilogram of moisture-free,ash-free wood is subjected to hydropyrolysis. In this case, the vaporstream contains 1.8 grams of NH₃ and 0.5 grams of H₂S. Due to thedifferent molar masses of NH₃ and H₂S, this equates to 0.106 moles ofNH₃ and 0.014 moles of H₂S. The molar ratio of NH₃ to H₂S is therefore7.4 to 1. In order to form (NH₄)₂S in an aqueous solution, two moles ofNH₃ are required for each mole of H₂S. The relative amounts of NH₃ andH₂S in the vapor stream leaving the hydropyrolysis reactor are more thanadequate to react all the H₂S in the stream with NH₃, and produce anaqueous solution of (NH₄)₂S.

Further, the interaction with hydrogen in the hydropyrolysis processconverts a significant fraction of the oxygen in the dry, ash-free woodinto water vapor in the vapor stream leaving the hydropyrolysis process.Even if the feedstock is completely dry, there is still a significantformation of water during hydropyrolysis of the wood feedstock, and theamount of water produced is sufficient to substantially and completelydissolve all of the NH₃ and H₂S present in the hydropyrolysis productvapor stream.

While all or almost all of the NH₃ leaving the hydropyrolysis reactorultimately goes into solution in the primary aqueous stream, thesolubility of H₂S in aqueous solutions depends on a variety of factors,such as temperature, pressure, and pH of the solution. The NH₃ insolution in the primary aqueous stream will render the solutionalkaline, and this will significantly increase the solubility of H₂S inthe alkaline aqueous solution. H₂S and NH₃ react spontaneously inaqueous solution to form (NH₄)₂S, though the sulfide may be present in adissociated form. However, not all the H₂S in the product vapor streamis likely to enter the primary aqueous stream when the process vaporsare cooled. A cooled vapor stream, containing a significantconcentration of H₂S, is still likely to result in practice. The variousembodiments of the process of the present invention, described above,provide means by which this remaining concentration of H₂S can beremoved from the cooled vapor stream, and, ultimately, reacted with NH₃and oxygen to form (NH₄)₂SO₄.

In actual practice, the biomass feedstock conveyed into thehydropyrolizer will also contain some moisture, so the actual amount ofwater vapor in the heated vapor stream from the hydropyrolizer willcontain significantly more water that would be the case if the feedstockwere bone dry. This phenomenon assists in removal of H₂S from the cooledvapor stream, since the concentrations of NH₃ and H₂S in the primaryaqueous stream will be even lower than they would be if the feedstockwere completely dry, meaning that more H₂S can be stripped from thecooled vapor stream in the condenser and separator of the embodiments ofthe process of the present invention, described herein above. Thesolubility of (NH₄)₂S in water is very high, and solutions of (NH₄)₂Scontaining up to 52% by mass of (NH₄)₂S appear to be commerciallyavailable.

TABLE A Composition of Wood Feedstock Initial Composition, Wood: InitialComposition MAF Basis % C (MF) 47.6 50.2 % H (MF) 5.7 6.0 % O (MF) 41.243.5 % N (MF) 0.2 0.2 % S (MF) 0.1 0.1 % ash (MF) 1.1 % moisture 4.3

TABLE B Yield of hot vapor products from hydropyrolysis of wood, on amoisture- and ash-free (MAF) basis Wood Hydropyrolysis Hot Vapor ProductYield (MAF Basis): Wt % Gasoline 16 Diesel 10 Char 13 Water 36 CO 8.4CO2 8.4 C1-C3 12.8 H2S 0.05 NH3 0.18

Not all biomass is equivalent, and a second feedstock, which differssignificantly from wood in terms of mechanical properties, growth cycle,and composition, was also tested. This feedstock was corn stover. Cornstover includes residues of corn stalks and husks, left over after thenutritious parts of the plant have been harvested. The sample examinedwas typical of most types of corn stover generated during harvesting ofcorn. The composition of the corn stover sample is presented on both anoverall basis (which includes moisture and ash in the feedstock) and ona moisture- and ash-free (MAF) basis in Table C. As can be seen in TableC, small but significant quantities of nitrogen and sulfur were presentin the corn stover, as was the case with the wood feedstock. As can beseen from the table, the corn stover sample contained far more ash andfar more moisture than did the sample of wood.

As with the wood feedstock, the ratio between hydrogen sulfide andammonia in the hot product vapor leaving the corn stover hydropyrolysisprocess is very important. The hydropyrolysis product vapor compositionof corn stover was found to be very similar to that of wood, on an MAFbasis. The relevant values are shown in Table D. One significantdifference between Tables B and D relates to the concentrations of NH₃and H₂S in the product vapor. The molar ratio of NH₃ to H₂S in theproduct vapor, in the case of corn stover, is 15.2. Again, there is morethan enough NH₃ present to react with the H₂S in the product vaporstream and form ammonium sulfide. As was the case with wood, there ismore than sufficient water formed, during hydropyrolysis of corn stover,to completely dissolve any ammonium sulfide, and carry it in solutionthrough the process of the present invention. It will be noted that thetotal masses in Table D add up to 106%. This is due to the fact that agiven quantity of moisture and ash-free corn stover reacts with hydrogenin the hydropyrolysis process, and the resulting products have a greatertotal mass than the feedstock that was reacted.

TABLE C Composition of corn typical stover sample Initial Composition,Corn Stover: Initial Composition MAF Basis % C (MF) 38.0 50.7 % H (MF)4.8 6.4 % O (MF) 31.2 41.6 % N (MF) 0.9 1.2 % S (MF) 0.1 0.2 % ash (MF)8.3 % moisture 20.0

TABLE D Composition of effluent vapor, hydropyrolysis of typical cornstover, on MAF basis Corn Stover Hydropyrolsyis Hot Vapor Product Yield(MAF Basis): Wt % Gasoline 15 Diesel 9 Char 15 Water 36 CO 8.4 CO2 8.4C1-C3 13.8 H2S 0.12 NH3 0.92

While in the foregoing specification this invention has been describedin relation to certain preferred embodiments thereof, and many detailshave been set forth for purpose of illustration, it will be apparent tothose skilled in the art that the invention is susceptible to additionalembodiments and that certain of the details described herein can bevaried considerably without departing from the basic principles of theinvention.

1. A hydropyrolysis process comprising: introducing biomass and hydrogeninto a hydropyrolyzer comprising one or more reactors; sufficientlydeoxygenating the biomass to provide a vapor product of thehydropyrolyzer comprising, in the gaseous state, deoxygenatedcondensable hydrocarbons, non-condensable gases, and water; cooling thevapor product to condense a liquid organic phase and a liquid aqueousphase comprising at least one species of the vapor product, includingammonia (NH₃), that is solubilized in the liquid aqueous phase; andphase separating the liquid aqueous phase from the liquid organic phaseand obtaining a gas phase NH₃ product or an aqueous ammonia product fromthe aqueous phase.
 2. The process of claim 1, wherein the hydropyrolyzercomprises multiple reactors in series.
 3. The process of claim 1,wherein the solubilized NH₃ is present in the aqueous phase in excess ofan amount that is consumed by reaction with H₂S to form (NH₄)₂S in theaqueous phase.
 4. The process of claim 3, wherein the aqueous ammoniaproduct is obtained following catalytically reacting the aqueous phasewith oxygen to substantially oxidize the (NH₄)₂S to (NH₄)₂SO₄.
 5. Theprocess of claim 1, further comprising separating, from the condensedorganic and aqueous phases, a cooled vapor phase comprising thenon-condensable gases including non-condensable hydrocarbons and H₂S. 6.The process of claim 5, further comprising treating the cooled vaporphase to substantially remove the H₂S.
 7. The process of claim 6,wherein the treating comprises contacting the cooled vapor phase with abed of sorbent or with a liquid wash.
 8. The process of claim 5, furthercomprising subjecting at least a portion of the cooled vapor phase tosteam reforming, in order to generate hydrogen.
 9. The process of claim1, wherein the method comprises obtaining a gas phase NH₃ product bysubjecting the liquid aqueous phase to sour water stripping.
 10. Theprocess of claim 9, wherein the gas phase NH₃ product is obtainedfollowing reacting the liquid aqueous phase with oxygen to substantiallyoxidize the (NH₄)₂S to (NH₄)₂SO₄, followed by subjecting the liquidaqueous phase to the sour water stripping.
 11. The process of claim 10,wherein reacting the liquid aqueous phase with oxygen is performedcatalytically.
 12. The process of claim 1, wherein the aqueous ammoniaproduct is obtained following reacting the liquid aqueous phase withoxygen to substantially oxidize the (NH₄)₂S to (NH₄)₂SO₄.
 13. Theprocess of claim 1, wherein the biomass contains moisture thatcontributes to the liquid aqueous phase.
 14. The process of claim 1,wherein the deoxygenated condensable hydrocarbons are substantiallyrecovered in the liquid organic phase and comprise hydrocarbons havingproperties corresponding to gasoline, diesel, and kerosene.
 15. Theprocess of claim 1, wherein the biomass contains nitrogen (N) and sulfur(S) in amounts such that both the NH₃ and H₂S are formed in the vaporproduct, with an amount of NH₃ being in excess of that required to reactwith the H₂S, to form (NH₄)₂S.
 16. The process of claim 1, wherein theliquid aqueous phase comprises more water than is sufficient to dissolve(NH₄)₂S that is formed by the reaction of the NH₃ with H₂S, initiallypresent in the vapor product.
 17. A method for preparing an ammoniaproduct, comprising: processing biomass in a hydropyrolyzer to obtainsolid char and a heated vapor product comprising hydrogen, carbonmonoxide, carbon dioxide, deoxygenated condensable hydrocarbons, andwater vapor; cooling the heated vapor product to condense, as separateliquid phases, an organic phase and an aqueous phase comprising NH₄OHthat is formed from the dissolution of NH₃ from the heated vapor productinto the aqueous phase; and separating the liquid phases and obtainingthe ammonia product as a gas phase NH₃ product or an aqueous NH₄OHproduct from the aqueous phase.
 18. The method of claim 17, wherein theaqueous phase further comprises (NH₄)₂S, resulting from the dissolutionof both NH₃ and H₂S from the heated vapor product into the aqueous phaseand reaction of a portion of dissolved NH₃ with dissolved H₂S.
 19. Themethod of claim 17, wherein the hydropyrolyzer comprises multiplereactors in series.
 20. The method of claim 17, wherein the ammoniaproduct is a gas phase NH₃ product that is obtained by subjecting theaqueous phase to sour water stripping.
 21. The method of claim 17,further comprising: separating, from the liquid phases, a cooled vaporphase comprising non-condensable hydrocarbons, and steam reforming atleast a portion of the non-condensable hydrocarbons to generate hydrogenthat is used for the processing of the biomass in the hydropyrolyzer.